Spectacles and parts of spectacles have in the past been manufactured using a wide variety of materials and manufacturing methods. In particular, spectacles have been made from metal and from a wide variety of plastic materials, e.g. thermoplastic resins.
Spectacles and parts of spectacles made from metals and plastic materials have the advantage that the shape can be adjusted, possibly after having added heat, for example in order to adapt the shape, curvature, etc. of the spectacle frame to the glasses or in order to adapt the spectacle frame to the user.
When manufacturing spectacle frames, a number of aspects have to be taken into consideration, including the weight of the frame due to e.g. user comfort when wearing the spectacles, the rigidity and toughness of the spectacles and parts of spectacles, etc.
Furthermore, the manufacturing cost is an aspect that has to be taken into consideration. Even further, the options for designing spectacle frames are of significant importance when manufacturing spectacle frames, since customer preferences are vital for the commercial success of the spectacle frames. Thus, flexibility in the manufacturing process is desirable as are the options for providing spectacle frames having a customer appealing appearance.
JP 61-233717 discloses a spectacle frame composed of composite reinforced resin, where a thermoplastic matrix resin is used and where the reinforcing material comprises short carbon fibres and SiC whiskers.
EP 0 332 540 A1 discloses a rigid composite structure, in particular for a spectacle frame, where a number of layers are used around a core and wherein a thermoplastic material is used as a matrix material. The core as well as the layers comprise material such as carbon, glass, aramid, etc.
A common problem, though, with components made of composite materials relates to the adjustment or adaptation of the components, for example when used for spectacle frames, where it normally will be necessary or desirable to adjust the shape and/or curvature of e.g. rim parts and browbars to the specific lenses and adjust the e.g. browbar and/or side members to the user. The method used when plastic materials are used, i.e. application of heat and bending/adjusting the components can not be used when composite materials are used since the materials will break, delaminate, be subjected to fibre pull-out and/or decompose.
A further example of the wide variations in construction of spectacle frames is disclosed in U.S. Pat. No. 4,222,640, which relates to safety spectacles and where an inner frame made of hard plastic material commonly used for spectacles is embedded in a relatively thick layer of polyurethane foam. The polyurethane foam has a number of advantages including that it is easy to mould and that it has elastic properties allowing the corrective lenses to be inserted without difficulty. Further, the foam provides a comparatively soft mounting of the lenses. Thus, there is no need to adjust the shape of the frame due to e.g. the shape of the lenses and/or due to user preferences since the foam is elastic. According to an embodiment, a continuous metal wire is embedded in the inner frame made of hard plastic material in order to assure that the spectacles are still fitting if the inner frame has suffered a crack. According to another embodiment, the side pieces may have a metal core surrounded by the layer of polyurethane foam.
A still further example of a spectacle frame is disclosed in GB 1 378 683, which relates to a spectacle temple or side bar, which is made of a substantially rigid plastics material which is moulded around a reinforcing wire and where the rear portion may be formed to fit the user's ear while it is softened by the application of heat.
A still further example of a prior art spectacle frame is disclosed in FR 1 399 533 (corresponding to GB 1 074 013), which spectacle frame has a pair of side frames hingedly connected to the lens mount portion of the spectacle frame. Each of the side frames is composed of layers of thermoplastic materials, including a center layer, in which an axially extending reinforcement, e.g. a metal wire reinforcement, is disposed. The thermoplastic material of the center layer has a lower flow temperature than the outer layers. Thus, when the side frame is heated to a temperature, where material of the center layer, but not the outer layers, is softened, the reinforcement element can be forced into the side frame. According to a particular embodiment, the two outer layers are shaped to completely surround the center layer after assembly of the thermoplastic material layers. Thus, the center layer having the lower flow temperature is in the form of a core part, in which the reinforcement element will be embedded after having been forced longitudinally through the assembly of the thermoplastic material layers. The thermoplastic material used according to this prior art document is for example cellulose nitrate, cellulose butyrate or cellulose acetate.
Still further examples of prior art spectacle frames and frame parts are disclosed in US 2003/0020866 A1, US 2007/0002271 A1, U.S. Pat. No. 4,988,479 A, FR 2 563 637 A1 and FR 2 785 058 A1.
Of these, US 2003/0020866 A1 relates to an end piece for the temple or side frame of a spectacle frame, where the temple is made of metal and where the end piece comprises a thermoplastic end piece substrate and an end piece cover made of shape-memory plastic.
US 2007/0002271 A1 relates to a spectacle frame, where the temples or side frames each has a core made of an elastically deformable material such as titanium, stainless steel, etc, and where each temple comprises an outer coating having a rigidity substantially greater with respect to the core.
U.S. Pat. No. 4,988,479 A relates to a method for producing a multi-layered material having a base block and at least one surface layer, which material may be used for eyeglass frames. The base block may be made of titanium and the method comprises spraying at least one surface layer on the base block.
FR 2 563 637 A1 discloses a multi-layered material for spectacle frames, which material has an aluminum core and a cladding made of titanium.
FR 2 785 058 A1 discloses a spectacle frame, which comprises a metal wire frame and hinges, which metal wire frame is embedded in a moulded layer of plastic material.